Little work has been done in examining student reasoning about organic spectroscopy. As a result, the number of available instruments for probing students’ unconscious commentary is small. Here we describe the creation and implementation of an instrument to explore students’ ability to solve spectra. We adapted the 3 Phase-Single Interview Technique (3P-SIT) previously used to uncover student reasoning with visual representations in biochemistry. The first phase probes the participant’s conceptual knowledge underlying a particular visual representation before being presented any representations. In the second phase the participant is given the representation to interpret, and in the third phase the participant evaluates and critiques the representation. The unique features of the 3P-SIT and the ways in which we adapted the protocol to examine students’ reasoning in the novel context of organic chemical spectra will be presented.